The present invention relates to an antenna device for a radio communications apparatus operating in dual frequency bands, and comprising one antenna element for each frequency band.
In radio communications apparatuses, in daily parlance known as mobile telephones, use is made of different antennae for different operational states in the apparatus. In the talk position of the apparatus, use is made of an antenna in which the most important requirements involve a high degree of efficiency.
Mobile telephones operate within different frequency bands, for example approx. 450 MHz in the NMT band, approx. 900 MHz in the GSM band and approx. 1800 MHz in the DCS band. There are also mobile telephones which are designed to be able to operate in more than one frequency band, and such constructions require antenna capacity in both frequency bands.
As regards the switching between stand-by position (or paging mode) and talk position, use is often made of mechanical switches which are based on the retraction or protraction of an antenna rod. To employ, in addition to such a switch, also a switch for switching between different frequency bands would appear to be clumsy and difficult to operate.
The present invention has for its object to design the antenna device intimated by way of introduction such that it obviates the requirement on the use of switches for switching between different frequency bands. The present invention further has for its object to design the subject matter of the invention such that this will have a high degree of efficiency in both frequency bands, and may be manufactured simply and economically and with the requisite mechanical strength.